Everything is designed to last between a few years and a decade, with the expectation that there's no point engineering for longer than that because something better will replace it by then. This feels bad but it's generally correct. Practically every aspect of technology is improving so fast there's little point trying to engineer things that last, because a stronger, cheaper, lighter, thinner thing will be available long before the thing has expired.

Agile is a response to this, not the cause.